Bioinformatics CS300 Crash course: Transcription and Translation - - PowerPoint PPT Presentation

Bioinformatics

CS300

Crash course:

Transcription and Translation Running Python in Docker or Online

Fall 2019 Oliver BONHAM-CARTER

Gene Expression Transcriptjon and Translatjon

Transcriptjon

copy a set of ingredients/instructions from a cookbook to create a recipe

Translatjon

use the recipe to create a dish

The Central Dogma

• f Molecular Biology

Animatjon: Central Dogma of Biology

https://dnalc.cshl.edu/view/16933-3D-Animation-of-DNA-to-RNA-to-Protein.html

Transcriptjon

• Transcribe specifjc regions of DNA – genes

– Human genome ~25,000 genes (just 1.5% of genome)

• RNA is the direct product of transcribing a gene (DNA)

– DNA -> RNA – same language (nucleotjdes)

T ransfer RNA (tRNA) Ribosomal RNA (rRNA) Messenger RNA (mRNA)

RNA vs DNA

• RNA – uracil replaces

thymine (no Ts in RNA)

• RNA – single

stranded (one backbone, no basepairs)

• (RNA – slightly

difgerent sugar)

• Transcriptjon occurs on the strand containing the gene

whose product is needed.

• The strand containing the gene is the antjsense strand.
• The RNA transcript is the complement of the antjsense

strand.

Genes exists on both strands of DNA…

Antjsense and Sense Strands of DNA –

relatjve to the gene being transcribed

Antjsense strand Sense strand

Genes have beginnings and ends - promoters and terminators

Transcriptjon

• Transcribe specifjc regions of DNA – genes

– Human genome ~25,000 genes (just 1.5% of genome)

• RNA is the direct product of transcribing a gene (DNA)

– DNA -> RNA – same language (nucleotjdes)

T ransfer RNA (tRNA) Ribosomal RNA (rRNA) Messenger RNA (mRNA)

Transcriptjon Video

https://www.dnalc.org/resources/3d/12-transcription-basic.html

Sense and Antjsense DNA

• Antisense is the non-coding DNA strand of a gene
• A cell uses antisense DNA strand as a template for producing messenger RNA

(mRNA) that directs the synthesis of a protein.

Add 2 eggs bhgty to the fmour qwtzptlrbn and stjr. introns exons

• In most eukaryotjc genes, coding regions (exons) are interrupted by noncoding regions (introns).

Introns do not contain the message and are removed from the RNA afuer transcriptjon but prior to translatjon. During the process of RNA splicing, introns are removed and exons joined to form a contjguous coding sequence.

Add 2 eggs to the fmour and stjr

Non-coding regions Coding regions

Exon and Introns

• Exons: a segment of a DNA or RNA molecule containing

informatjon coding for a protein or peptjde sequence.

• Eukaryotjc pre-mRNA contains exons and introns*
• *some pre-mRNAs contain only one exon

Splicing Exon Material

Proteins are made of amino acids

The Genetjc Code: RNA into Protein

• Start and Stop codons
• First codon of

many transcripts is “AUG”, which codes for methionine

• Codons UAA, UAG,

and UGA indicate the end of the transcript

• Triplet code
• Combinatjons of three nucleotjdes code for one amino acid
• Three nucleotjdes = codon
• Redundancy
• Sometjmes >1 codon codes for same amino acid
• 20 amino acids, 64 possible codons

Another Triplet Table

Antjsense strand Sense strand

• The informatjon from DNA is rewrituen in a new

language: RNA

Translatjon

Translatjon Videos

• mRNA Translatjon (2 mins)

– htups://www.youtube.com/watch?v=8dsTvBaUMvw

• Protein Synthesis and the Lean, Mean Ribosome Machines (7

mins)

– htups://www.youtube.com/watch?v=h5mJbP23Buo

• DNA transcriptjon and translatjon (includes gene expression, 7

mins)

– htups://www.youtube.com/watch?v=2BwWavExcFI

Genes vs Gene Expression

Of the many recipes in the cookbook…

… Only transcribe and translate 4th of July recipes in July … Only transcribe and translate the Thanksgiving turkey recipe in November

All genes are present in the genome genes only expressed when needed

• Prepare to run some commands for Docker …
• Or, wait for a few slides and run Python3 shell

in your browser online

• Note: If you are not using ToolBox, Docker

should already be working in the background

• Navigate to where you have stored your

docker_getMeToThePython directory.

Mac and Windows ToolBox: find and run the “Docker QuickStart Terminal” Note: See file, quickStartCommands.md, for these commands Note: The Docker ToolBox commands to initiate server

Windows Quickstart Command: "C:\Program Files\Git\bin\bash.exe" --login -i "C:\Program Files\ Docker Toolbox\start.sh" MacOS Quickstart Command: bash --login '/Applications/Docker/Docker Quickstart Terminal.app/ Contents/Resources/Scripts/start.sh'

If your server was properly initialized then, you should see this cute whale.

• Two ways to run Python3 in DockerQS or bash shell
• See file, commands.md, for these notes

– docker run -t python3 – Or, build the container and run Python3 there

• docker build -t py_play .

– Mount a drive and then use bash to run

Python3

• docker run -it --mount

type=bind,source=$PWD,target=/home/py_play py_play

• Or, try Python3 programming using an

interactive shell from repl.it

• Link: https://repl.it/languages/python3

• Some trouble to make Python3 work with Docker ToolBox
• Install and use Python3 however you want!
• Get Python3 from the Python Software Foundation
• Login http://www.python.org/downloads

• Download and install the version of Python3 for your OS being sure to add the PATH

to the environmental variables (check the path option!)

• Ask questions if you have trouble installing the program
• Check with the installation material to learn how to launch
• Python3 from your machine.

Python3

#Calculating values 3 / 4 2 * 6 3.1415 – 2.718 x = 1 y = 2 print(x+y) result = x + y print(“The result is :”,result)

Python3

# Integers, counting numbers num_int = 1 # Floats, decimals num_float = 3.1415 # Strings s_str = ” Hello World” # Combining variables in print statements x_int = 1 print(" The integer variable is :", x_int) num_float = 3.14 print(" The float variable is :", num_float) s_str =("Hello World'') print(" The integer is equal to", s_str)

Calculate

3 + 4 # Addition 3 − 4 # Subtraction 3 4 # Multiplication

• 3 / 4 # Division of 3 by 4

# Modulus; Returns the remainder from the division 3 4 ∗ ∗5 ∗ ∗5 3%4 # Powers; raise three to the power of four = 3 3 3 3 = 3^4 = pow(3,4)

Strings

# Remember each char of a string has own position s_str = "ABC" s_str[0] = 'A' s_str[1] = 'B' s_str[2] = 'C' s_str[200] = ?? # Another way to iterate # through a string using its length for i_int in range(len(s_str)): print(s_str[i_int])

Counting and Finding

# Getting input from a user resp_str = input(“Enter your name :”) print(" Hello",resp_str,"!") # Determine number of chars in a string lengthOfName_int = len(resp_str) # Find a subset-string in the string resp_str.find("M") resp_str.find("A") resp_str.find("R") resp_str.find("K") resp_str.find("ARK")

Counting and Finding

Find char occurrence in a string resp_str = “Hello!!” resp_str.count("H") resp_str.count("l") Find number of specific triples in string. resp_str = “Hellollollo!!” resp_str.count("llo") resp_str.find("llo")

Getting Input

Find char occurrence in a string resp_str = “Hello!!” resp_str.count("H") resp_str.count("l") Find number of specific triples in string. resp_str = “Hellollollo!!” resp_str.count("llo")

A Short Program Watch for tabs that define code blocks

print("Welcome to the program!") prmpt_str = " Please enter your name :" # place the string above into input statement name_str = input(prmpt_str) print(" Your name is :",name_str) print(" And is <<",len(name_str),">> chars long!") # print the chars on lines print(" What are the characters in the string? ") for i in range(len(name_str)): # note the tabs for this block! # we iterate through the positions in string print(" + char :",name_str[i]) # findout how many a's are in the name numChar_int = name_str.count("a") print(" The number of a's in your name :",numChar_int)

For this code, see file, pythonDemo.py, in your sandbox.

Consider This ...

• Group work
• Write a short program in Python3 that …
• Accepts a short sequence of DNA (that you type in) and

counts the occurrences of:

– A’s – T’s – G’s – C’s – “AT”, “TA” – “GC” and “CG”

Then Consider This ...

• Now, go get a real piece of DNA and try out your

program

• Link for organism: Gordonia phage Orchid, complete

genome,

– https://www.ncbi.nlm.nih.gov/nuccore/NC_030915.1?repor

t=fasta

• What results did you find in terms of the pairs of AT’s,

TA’s, GC’s and CG’s?

• Are the numbers of pairs similar or dissimilar?